The present invention relates to a connection method and connection structure for making a connection of a clad electric wire with a contactor, terminal, or other electric wires.
As related connection methods, there are a first related technique described in Japanese Patent Application Publication No. H7-70345 and a second related technique described in Japanese Patent Application Laid-Open Publication No. H9-293577.
In the above-described first related technique, a clad electric wire is clamped between a contact member consisting of a metal plate and resin parts and the resulting clamping is caused to undergo ultrasonic excitation. Ultrasonic excitation is performed of the metal and resin whose heat conductivities are different from each other. For this reason, a difference occurs between the two in terms of the heat generated therefrom, with the result that the elimination effect of eliminating a clothing portion of the clad electric wire by ultrasonic excitation is decreased and so it is impossible to smoothly eliminate the clothing portion. As a result of this, the clothing portion of the clad electric wire remains to exist at a portion of connection of the clad electric wire with the contact member, or gases generate from the clothing portion that remains to exist. Whereby, there is the possibility that the contact resistance will increase. Also, there is the possibility that a conductor portion of the clad electric wire and the contact member will deteriorate due to the gases generated.
On the other hand, in the second related technique, it is necessary to perform the operation of twisting a plurality of clad electric wires. Therefore, the operating efficiency is bad. Also, since the clad electric wires are brought into a state of their being twisted together, it is difficult, at the time of ultrasonic excitation, to reliably eliminate the clothing portion of the clad electric wire and so the clothing portion remains to exist at the portion of connection. As a result of this, there is the possibility that the contact resistance will increase and gases will generate to cause deterioration of the conductor portion of the clad electric wire.
In view of the above, an object of the present invention is to provide a connection method and connection structure for a clad electric wire that enables the reliable elimination of the clothing portion of the clad electric wire by ultrasonic excitation to thereby decrease the contact resistance and that enables the prevention from deterioration of the conductively connected portion, conductor portion, etc.
To attain the above object, the present invention provides a connection structure for making a conductive connection between a clad electric wire and a member, which is comprised of a member having a conductivity, a clad electric wire to be superposed on the member, a resinous layer disposed between the member and the clad electric wire, and a pair of resin parts clamping the superposed portions between the clad electric wires and the member. The clad electric wire has a conductor portion and a resin-made clothing portion covering the outer periphery of the conductor portion. The superposed portions have a pressure applied thereto via the resinous parts and ultrasonic excitation is performed with respect thereto. As a result of this, the clothing portion is scattered and fused and as a result the resinous portion is fused. As a result, the conductor portion and the member are conductively connected and the mated resinous parts are fused together in the state of their clothing the superposed portions.
The above-described connection structure is provided through the following method. First, the clad electric wire and the member are superposed one upon the other. Then, the superposed portions between the clad electric wires and the member are clamped by the pair of resinous parts. At this time, the resinous layer is disposed between the clad electric wire and the member. Next, the superposed portions have a pressure applied thereto via the resinous parts and are ultrasonically excited.
In the above-described structure and method, in a state where the resinous layers are disposed between the clad electric wires and the member, ultrasonic excitation and pressure application are performed with respect to the resulting assembly. Accordingly, the resinous clothing portion of the clad electric wire is ultrasonically excited in direct contact with the resinous layer without directly contacting with the member.
The difference in heat conductivity between resins is very small compared to the difference in heat conductivity between resin and metal. Therefore, when ultrasonically excited, the clothing portion and the resinous portion equally generate heat. For this reason, the clothing portion is excellently fused and scattered and so it is very unlikely that the clothing portion will remain to exist between the conductor portion and the member. Accordingly, the increase in contact resistance due to the residual existence of the clothing portion and the deterioration of the conductor portion and the member due to the generation of gases are prevented.
The resinous layer may be formed integrally with one of the resinous parts and the member may be held between the one of the resinous parts and the resinous layer.
In the above-described construction, by superposing the clad electric wire on the resinous layer, the resinous layer is disposed necessarily between the clad electric wire and the member. Therefore, the operation efficiency of conductive connection is enhanced.
The member may be constructed of a terminal metal fitting equipped with a connection piece portion. This connection piece portion is embedded into one of the resinous parts.
In the above-described construction, in a state where the increase in contact resistance and the deterioration in the terminal metal fitting have been prevented, the clad electric wire and the terminal metal fitting are connected.